Apatosaurus excelsus

This famous long-necked, long-tailed wonder belongs to a group called "sauropods." This group of animals are the largest to ever roam our planet. Apatosaurus was an herbivore (plant-eater) and it walked on all four legs. To reach tree tops, it may have reared up on its hind legs and used its tail as a "third leg."

Image credits: main image, Rick Spears.